For use in a suspension system of an automobile, a bearing device for a vehicle wheel which rotatably supports the vehicle wheel has been known. In the bearing device for a vehicle wheel, an outer member is fixed to a knuckle constituting the suspension system. In the bearing device for a vehicle wheel, an inner member is disposed on an inner side of the outer member, and rolling elements are interposed between the outer member and the inner member. In this manner, the bearing device for a vehicle wheel constitutes a rolling bearing that allows the vehicle wheel attached to the inner member to freely rotate.
In such a bearing device for a vehicle wheel, when muddy water or dust enters into an annular space formed between the outer member and the inner member, the rolling elements and the like are damaged to decrease the life of the bearing. Also, when grease filled in the annular space leaks, the rolling elements and the like are damaged to decrease the life of the bearing. For this reason, to prevent the entrance of muddy water and dust as well as the leakage of grease, the bearing device for a vehicle wheel includes a seal member for sealing the annular space. This is disclosed in, for example, Patent Literature 1, Patent Literature 2, and Patent Literature 3.
A bearing device for a vehicle wheel described in Patent Literature 1 includes an outer member, an inner member, rolling elements interposed between the outer member and the inner member, and a seal member for sealing an outer-side end of an annular space formed between the outer member and the inner member. However, when muddy water flows along the outer member and reaches the seal member, the bearing device for a vehicle wheel may catch foreign matters contained in muddy water, resulting in that the seal member is broken or worn. That is, the sealing performance of the seal member may lower.
Thus, in a bearing device for a vehicle wheel described in Patent Literature 2, to prevent muddy water from flowing along an outer member to reach a seal member, the configuration of the seal member is designed to provide a weir portion on the outer circumference on the outer member. In a bearing device for a vehicle wheel described in Patent Literature 3, a separate component is fitted to an outer member to form a weir portion on the outer circumference of the outer member. However, in these bearing devices for a vehicle wheel, when muddy water hits against the weir wall face of the weir portion and scatters, the scattered muddy water may splash over the weir portion and reach the seal member (see arrows F in FIGS. 24A and 24B), failing to eliminate the concern that the seal member is broken or worn. That is, disadvantageously, the concern that the sealing performance of the seal member lowers cannot be eliminated.
Further, in the bearing device for a vehicle wheel described in Patent Literature 2, a core metal of the seal member extends along the outer-side end face of the outer member in the radial outward direction, and a seal rubber encloses the outer edge of the core metal to constitute the weir portion on the outer circumference of the outer member. However, in such a bearing device for a vehicle wheel, hub bolts are press-fitted to a vehicle wheel-attaching flange and heads of the hub bolts are in proximity of the outer member. Thus, when the height of the weir portion is increased, the hub bolt cannot be disadvantageously exchanged (see FIG. 25).
Against this backdrop, a bearing device for a vehicle wheel provided with guide grooves for passing the respective hub bolts therethrough on the outer circumference of the weir portion has been proposed. In such a bearing device for a vehicle wheel, due to the guide grooves, the diameter of the core metal cannot be made large and thus, does not protrude so much from at least the outer circumference of the outer member. However, there is a demand for increasing the stiffness of the core metal to suppress a distortion of the fitting portion and increasing the force to fit the core metal to the outer member. That is, there is a demand for increasing the stiffness of the core metal to suppress a distortion of the fitting portion and increase the force to fit the core metal to the outer member, thereby preventing the seal member from being detached and water from entering into the fitting portion between the seal member and the outer member.